SGO: Combo Therapy Gets High Marks for Vulvar Ca

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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Note that in this study, a combination of radiation therapy plus weekly cisplatin yielded a higher response rate than previously achieved with radiation and concurrent cisplatin plus 5-fluorouracil chemotherapy.

ORLANDO -- Two-thirds of patients with locally advanced vulvar cancer had clinical complete responses and half had pathologic complete responses with concurrent cisplatin and radiation, according to an interim analysis of a phase II trial.

The planned interim analysis, for the 68% of patients who completed treatment, topped those seen in a previous Gynecologic Oncology Group (GOG) trial by delivering a higher dose of radiation in a more patient-friendly fractionation schedule.

"I would conclude that, although there is still considerable room for improvement, the results of GOG 205 would indicate that this is a reasonable standard for treatment of locally advanced squamous-cell carcinoma of the vulva and should be the treatment program for future comparisons in prospective trials," said David H. Moore, MD, of St. Francis Hospital in Indianapolis.

Moore reported the findings here at the Society of Gynecologic Oncology meeting.

Asked whether the treatment regimen used in GOG 205 should be the standard of care for clinical practice, Moore demurred, instead reiterating his belief that the regimen is a reasonable standard. Noting the rarity of the cancer, he added that a randomized comparison to identify an optimal regimen is unlikely.

Historically, locally advanced vulvar cancer (T3-4) been viewed as a surgical disease, often extensive in nature, necessitating urinary diversion and/or colostomy. However, in the 1980s, clinical thinking about the disease began to change.

Several case series showed good results with radiation followed by surgery, which was associated with improved survival and high rates of bladder and rectal preservation.

The encouraging results of single-center series led to the GOG 101 trial, which introduced concurrent cisplatin-5 FU chemotherapy with radiation therapy. About half the patients had clinical complete responses, and only 3% of patients had unresectable residual disease (Int J Radiat Oncol Biol Phys 1998; 42: 79-85).

"There was still room for improvement, because half the patients still had residual microscopic disease, and in eight patients, the vulva was the initial site of recurrence," said Moore.

Several design issues of GOG 101 were addressed in GOG 205. Cisplatin-5FU had become inconsistent with current chemotherapy practices and was changed to weekly infusions of cisplatin alone.

The GOG 101 radiation dose of 47.6 Gy was intentionally low because all patients were expected to undergo surgery, said Moore. In GOG 205 the total dose was increased to 57.6 Gy.

Finally, GOG 101 required twice-daily radiation therapy, and a treatment break occurred between the first and second cycles of therapy. In GOG 205, radiation therapy was administered once daily, and the treatment break was eliminated.

The primary endpoint of GOG 205 was pathologic complete response. The rarity of the disease was emphasized by the fact that investigators needed almost four years to accrue 58 evaluable patients.

GOG 205 had a design that was consistent with regimens for other squamous-cell cancers, including anal and cervical cancer, both of which are treated with chemoradiation, in addition to surgery, noted invited discussant Akila N. Viswanathan, MD, of the Dana-Farber Cancer Institute in Boston.

In response to a question, Moore said the higher dose of radiation therapy probably accounted for the higher response rate in GOG 205. Elimination of the treatment break might have been a factor, but the change to platinum-only chemotherapy did not explain the improved results, he said.

"We are left with the question of what should be the current standard of care," said Viswanathan.

Moore said the GOG 205 regimen should not be considered "the" regimen for locally advanced squamous-cell carcinoma of the vulva because the current results leave room for additional improvement.

Investigators should continue the search for an optimal therapy for the disease, he added.

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